The ability of flywheels to accept and release energy over relatively short time periods has been known for many years and energy storage flywheels have been used, or proposed for use, in a variety of applications. Such proposed and actual use applications include motor vehicle applications and stand alone supplemental energy sources.
There is shown in FIG. 1 a simplified view of a conventional flywheel energy storage system 100 used for storing kinetic energy. The conventional flywheel system 100 includes a flywheel assembly 104 disposed in a flywheel housing 102. Further, the flywheel housing is configured and arranged so such flywheel assemblies 104 are run under vacuum, in order to avoid drag on the flywheel. The systems are evacuated with standard vacuum pumps, e.g. turbo pumps, and then sealed, preferably by pinching off and then fusing the end of a copper tube, thus forming an all-metal seal, which is impervious to air. The materials that make up the flywheel system, however, may entrain or evolve substantial quantities of materials that may be released within the system when under a vacuum, thus causing a reduction of the vacuum during operation. To partially deal with that problem, a drag pump 106 for example, is incorporated into the flywheel assembly 104 for pumping gases from the flywheel housing 102 into a separate gas storage chamber 108.
The typical flywheel assembly 104 includes a flywheel, a shaft to which is secured the flywheel and one or more bearings or bearing assemblies that rotatably support the shaft. Traditionally, flywheels have been made of metal, e.g., high strength steel. More recently, flywheels have been fabricated using fiber composite materials, e.g., fiberglass or carbon wound with a resin binder, thereby making flywheels that are lighter in weight and capable of operating at higher speeds than the traditional metal flywheel assemblies operate.
Because the rotatable supporting of the rotating flywheel results in the production of heat energy in the bearings or bearing assemblies, the operational life of the flywheel assembly 104 as well as the operational life of the flywheel energy storage system 100 is dependent in part upon the ability of the flywheel energy storage system to dissipate heat energy developed in the bearings or bearing assemblies. One conventional technique to dissipate this heat energy involves cooling the fluid that lubricates the bearings or providing a separate fluid cooling system for the bearings. This technique, however, necessarily requires that the lubricated bearings and/or cooling systems be sealed and not exposed to the vacuum environment within the flywheel housing 102 as well as providing a mechanism for putting the cooling medium in thermal connection with the environment outside of the flywheel housing.
Another technique involves the use of the supporting structure(s) for the flywheel and the bearings or bearing assemblies as a thermal conduction path to conduct the heat energy of the bearings to the flywheel housing 102. The heat energy is thence communicated to the external environment via the flywheel housing. Such a heat dissipation technique, however, is not compatible with flexible bearing mounting arrangements.
It thus would be desirable to provide a new and improved device or mechanism that dissipates heat energy from a bearing assembly in particular the outer race of a bearing assembly to the external environment. It also would be desirable to provide such a new heat conducting device or mechanism that conducts heat energy from a bearing to a heat sink while allowing relative axial and radial motion. It would be more particularly desirable to provide such a heat conducting device or mechanism that, when used in a flywheel energy storage system, would provide a thermal conduction path that more efficiently conducts the heat energy from the bearing assembly to the external environment, particularly when compared to devices embodying non-fluidic prior art techniques. Such a heat conducting device or mechanism preferably would be simple in construction and less costly than prior art devices and such methods for conducting heat energy from bearings would not require highly skilled users to utilize the device.